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The effect of time (or corrosion products formation) on corrosion rate of carbon steel pipe in aerated 0.1 N NaCl solution under turbulent flow conditions was investigated. Tests were conducted using electrochemical polarisation technique by determining the limiting current density of oxygen reduction in Reynolds number (Re) range of 15 000 to 113 000 and temperature range of 30-60 • C. The effect of corrosion products formation on the friction factor increase was studied and discussed. Empirical correlations for limiting current density as a function of Re were obtained at various solution temperatures for clean surface and for corroded surface. It was found that formation of corrosion products with time decreases the corrosion rate at low Re and temperature, while it increases the corrosion rate at high Re and temperature. As the corrosion products formed the surface roughness increased leading to increase the friction factor depending on temperature, Re, and corrosion rate.On a analysé l'effet du temps (ou la formation de produits de corrosion) sur la vitesse de corrosion d'un tuyau d'acier au carbone dans une solution 0.1 N NaCl aérée dans des conditions d'écoulement turbulent. Des essais ontété réalisésà l'aide de la technique de polarisationélectrochimique en déterminant la densité de courant limité de la réduction de l'oxygène dans l'écart de nombres de Reynolds de 15000à 113000 et dans l'échelle de température de 30 • Cà 60 • C. L'effet de la formation de produits de corrosion sur l'augmentation du facteur de frottement aétéétudié et discuté. Les corrélations empiriques pour la densité de courant limité comme fonction du nombre de Reynolds ontété obtenuesà diverses températures de solution pour une surface propre et une surface corrodée. On a découvert que la formation de produits de corrosion avec le temps réduit la vitesse de corrosionà une température et un nombre de Reynolds bas tout en augmentant la vitesse de corrosionà une température et nombre de Reynoldsélevés. Pendant que les produits de corrosion se formaient, la rugosité de la surface augmentait, ce qui a menéà une augmentation du facteur de frottement selon la température, le nombre de Reynolds et la vitesse de corrosion.

Dispersions of oil in water are encountered in a variety of industrial processes leading to a reduction in the performance of the heat exchangers when thermally treating such two phase fluids. This reduction is mainly due to changes in the thermal and hydrodynamical behavior of the two phase fluid. In the present work, an experimental investigation was performed to study the effects of light oil fouling on the heat transfer coefficient in a double-pipe heat exchanger under turbulent flow conditions. The effects of different operating conditions on the fouling rate were investigated including: hot fluid Reynolds number (the dispersion), cold fluid Reynolds number, and time. The oil fouling rate was analyzed by determining the growth of fouling resistance with time and through pressure drop measurements. The influence of copper oxide (CuO) nanofluid on the fouling rate in the dispersion was also determined. It was found that the presence of dispersed oil causes a reduction in heat transfer coefficient by percentages depending on the Reynolds number of both cold and hot fluids and the concentration of oil. In addition, the time history of fouling resistance exhibited different trends with the flow rates of both fluids and its trend was influenced appreciably by the presence of CuO nanofluid. K E Y W O R D S copper oxide, dispersion, double-pipe heat exchanger, fouling, heat transfer, nanofluid, oil Heat Transfer-Asian Res.

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